>
> I am reposting updated message as my mail server was down due to T-1
> upgrade.
> All response are most welcome amd encouraged!  Please RePost previous
> responses!
>
> PI>>> Telephone handset Audio into A/D converter sampling 8-bit bytes at
> PI>>> 22,050 sample rate with serial data fed to UART(16550) outputting 57,600
> PI>>> bit rate to MAX-232 RS-232 driver.
>
> PI>Why bother with 22,050 samples/second with telephone handsets?  They
> PI>were designed for a frequency range of ~300 to ~3000 Hertz.  Most of
> PI>the carbon microphones and little speakers used in handsets just don't
> PI>have the frequency response to justify this high a sample rate.
>
> PI>Telephone companies chose 8,000 8-bit samples/second to give an upper
> PI>frequency response of ~4000 Hertz (Nyquist limit).
>
> 'Scuse me for the bungled numbers.  I composed the Email from 3
> categories of calculations not interchangeable.
>
> The following is more reflective of reality:
> 57,600 baud Port * .8=46080 net data baud (less start & stop bits) /8
> (bits per byte)=
> 5760 bytes/sec  / 2 = 2880 max Nyquist frequency.
>
> I am going to try PIC 16c74 A/D sampling to its UART with BASIC and  'C'
> code.
> Does anyone know the Maximum A/D sampling and UART port speeds when
> using:
> 1> PIC or ETI BASIC
> 2> compiled 'C' code (.OBJ)
>
> ALSO, does anyone have info for intializing 16550 UART as standalone
> FIFO-serial/parallel port interface
>
>
        Having just finished a project with the 16550, I can tell you it
is very easy to use and initialize...  I would suggest checking out
National Semiconductor's web site (www.natsemi.com) where they have .PDF
documents on line with the complete 16550 manual being one of them
(you'll need to do a search on 16550 to find it).  The only thing I found
annoying about the 16550 was the Intel-ish practice of requiring the R*
and W* lines to only be active when CS* is.

Good Luck!


Larry Battraw